function sum(flag, ...args) {
    // console.log(args)
    args.forEach(item => {
        // console.log(item)
    })
}
sum(100, 1, 2, 3)

let arr = [1, 2, 3]
let [s1, ...s2] = arr
console.log(s1)
console.log(s2)
    // 
    // 剩余参数
let a = function(a, b, ...args) {
    console.log(a, b, args)
}
a(1, 2, 3, 4)